S.F.P. HiVeg™ Agar Base

Principle and Interpretation

S.F.P. HiVeg Agar Base is prepared by using HiVeg hydrolysate No. 1 which is free of BSE/TSE risks. S.F.P. HiVeg Agar Base is the modification of S.F.P. (Shahidi-Ferguson Perfringens) Agar Base which is based on the formulation developed by Shahidi and Ferguson (1). The medium along with egg yolk emulsion and supplement containing Kanamycin and Polymyxin B as the selective agents give high degree of selectivity for Clostridium perfringens. HiVeg hydrolysate No.1, Papaic digest of soyabean meal and yeast extract supply nitrogenous compounds, carbon, sulphur, vitamin B complex etc. necessary for the growth of Clostridia. Sodium bisulphite and ferric ammonium citrate are the hydrogen sulphide (H₂S) indicators. Clostridia reduce sulfite to sulfide, which reacts with iron and forms a black iron sulfide precipitate. This results in the formation of black colonies. Kanamycin and Polymyxin B used in the medium allow a better recovery of vegetative cells and spores of Clostridium perfringens than either Polymyxin B or Sulphadiazine alone (2). Some strains of Clostridium perfringens may form an opaque zone around the colony due to their lecithinase activity. Lecithinase positive facultative anaerobes may grow on SFP HiVeg Agar Base making the plates completely opaque and thus may mask the egg yolk reaction of Clostridium perfringens. Black colonies appearing on this medium may be of organisms other than Clostridium perfringens, so confirmatory tests should be carried out for identification.